10 Reasons Why the Multiverse Could Be a Reality

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In 1954, Hugh Everett III, a 27-year-old Princeton University graduate student, was enjoying sherry with friends and discussing physics. During their conversation, Everett conceived a groundbreaking idea to address a persistent issue in quantum mechanics, which examines reality at the microscopic scale. In quantum theory, particles like electrons exist in a superposition, meaning they occupy multiple states simultaneously. However, at the macroscopic level, objects appear to exist in a single state. This raises the question: how does our observable world emerge from these countless possibilities? [source: Byrne].

Everett, an undeniably creative thinker, had a sudden and extraordinary insight that was both ingenious and unconventional. In a simplified explanation, he envisioned not a single reality with one definitive state, but a multiverse teeming with countless realms where every quantum possibility coexists simultaneously [source: Byrne].

Everett's groundbreaking idea, which formed the core of his 1957 doctoral thesis, was so unconventional that he struggled to have it published in a scientific journal. This experience reportedly left him so disillusioned that he abandoned theoretical physics entirely and pursued a research position at the Pentagon [source: multiverse/">Hooper].

Over the decades, Everett's multiverse concept has slowly gained acceptance among physicists. It has also embedded itself in popular culture, becoming a recurring theme in science fiction and captivating countless individuals who may not grasp the complexities of quantum theory. The idea that every decision we make—whether it's choosing a life partner, a home, a hair color, or even a meal—creates a parallel universe where an alternate version of ourselves makes a different choice is undeniably fascinating [source: Hooper].

Do we inhabit a multiverse? While there's no definitive answer, here are 10 compelling reasons why this possibility deserves serious consideration.

10: Schrödinger's Cat Is No Longer a Concern

Before Everett introduced the multiverse theory, physicists faced a perplexing dilemma. They had to apply one set of rules to the subatomic realm studied by quantum mechanics and another set to the macroscopic world we observe daily. This disparity forced them to grapple with complex and often contradictory ideas.

For instance, in quantum mechanics, particles lack defined properties when unobserved. Instead, their state is described by a wave function, encompassing all potential properties. However, in a single universe, only one possibility can manifest when observed. This concept is famously illustrated by Schrödinger's cat paradox, where a cat in a box is simultaneously alive and dead until the box is opened, forcing it into one state.

In a multiverse, however, you needn't worry about your curiosity determining the cat's fate. Instead, opening the box creates two realities: one where you find a lifeless cat and another where you enjoy the company of a purring feline [source: Merali].

9: A Pathway to Infinite Realities

In a 2011 interview, Columbia University physicist Brian Greene, author of "The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos," explained that the size of the universe remains uncertain. It could be immensely vast yet finite, or space might extend infinitely in all directions, a concept many of us intuitively imagine.

If space is infinite, Greene argues, it implies the existence of a multiverse with countless parallel realities. To understand this, consider the universe and its matter as analogous to a deck of cards. Just as a deck has a finite number of cards, matter exists in a finite number of forms. Shuffling the deck repeatedly will eventually produce repeated sequences. Similarly, in an infinite universe, matter must eventually repeat and arrange itself in familiar patterns. A multiverse, with its infinite parallel realms, elegantly explains this necessity for repetition [source: Greene].

8: It Offers an Explanation for the Universe's Origin and Destiny

As humans, our brains are wired to seek patterns, driving our desire to uncover the origins and conclusions of every story, including the universe's. If the Big Bang marked the universe's beginning, what sparked it, and what preceded it? Will the universe eventually end, and what follows? These are questions that captivate curious minds.

A multiverse could offer answers to these profound questions. Some physicists propose that the multiverse consists of infinite regions known as braneworlds. These braneworlds exist in multiple dimensions, but we can only perceive the three spatial dimensions and the fourth dimension of time within our own braneworld.

According to some theories, these braneworlds are like slabs stacked together, similar to slices of bread in a bag. While they usually remain separate, occasional collisions between them could trigger cataclysmic events, such as repeated Big Bangs, allowing parallel universes to reset themselves endlessly [source: Moskowitz].

7: Observational Data Hints at the Possibility of a Multiverse

The European Space Agency's Planck orbital observatory is collecting data on the cosmic microwave background (CMB), the residual radiation from the universe's early, high-energy phase.

This research has also uncovered potential evidence of a multiverse. In 2010, a team of scientists from the UK, Canada, and the US identified four unusual circular patterns in the CMB. They theorized that these marks were essentially scars from collisions between our universe and others [source: Zyga].

In 2015, ESA researcher Rang-Ram Chary made a similar finding. Chary removed the CMB model and all known elements—stars, gas, interstellar dust—from the observatory's sky map. What remained should have been nearly empty, aside from background noise.

However, Chary detected scattered patches in the cosmic map, approximately 4,500 times brighter than expected. He proposed that these patches could be remnants of a collision between our universe and a parallel one.

As Chary explained to EarthSky.org, unless an alternative explanation is found, "one must conclude that Nature may indeed be playing dice, and our universe is just one among countless others" [sources: Byrd, Sokol].

6: The Universe's Vastness Makes Parallel Realities Plausible

The possibility of a multiverse remains open because we cannot definitively prove its non-existence, even if we haven't observed any parallel realities.

While this might sound like a clever argument, consider this: Throughout history, we've discovered phenomena we never knew existed and witnessed events—like the 2008 global financial crisis—that were once deemed impossible. Such occurrences are known as black swan events, a term inspired by philosopher David Hume's observation that people assumed all swans were white until they encountered a black one [source: Taleb].

The sheer scale of the universe makes the multiverse theory more credible. The universe is unimaginably vast, possibly infinite, meaning we might never detect everything within it. Given that the universe is roughly 13.8 billion years old, we can only detect light that has had time to reach us. If a parallel reality lies beyond 13.8 billion light years, it would remain undetectable, even if it existed in dimensions we could perceive [source: Ball].

5: A Multiverse Aligns Better with Atheistic Perspectives

Stanford University physicist Andrei Linde noted in a 2008 interview that even minor changes to the physical laws would make life impossible. For instance, if protons were just 0.2 percent heavier, they would become unstable, breaking into simpler particles and preventing the formation of atoms. Similarly, slightly stronger gravity would compress stars like our sun, causing them to burn out in a few million years—far too quickly for life on a planet like Earth to develop. This is referred to as the "fine-tuning problem."

Some interpret this precise balance as evidence of a divine creator, posing a challenge for atheists. However, the multiverse theory offers an alternative explanation: our universe might simply be one of many, where the conditions for life happen to align perfectly.

As Linde explained in an interview with Discover magazine: "The existence of multiple universes is a logical possibility. While some might attribute our universe's conditions to divine intervention, the universe itself could be endlessly replicating in every possible form" [source: Folger].

4: Time-Travelers Can't Alter History

The "Back to the Future" (BTTF) trilogy has captivated audiences with its portrayal of time travel. While no one has invented a garbage-fueled DeLorean capable of traversing time, some scientists believe time travel could be theoretically feasible [source: Russon].

If time travel were possible, we might face the same dilemma as BTTF's Marty McFly—accidentally altering a past event and disrupting history. In the first film, McFly unintentionally prevents his parents from meeting, jeopardizing his own existence and forcing him to ensure they fall in love.

As Gizmodo's George Dvorsky explained in a 2015 article, a multiverse would render such complications irrelevant. "Alternate worlds mean there's no single timeline to disrupt," he wrote. Instead, any changes made in the past would simply create new parallel universes.

3: Our Reality Could Be a Simulation Created by an Advanced Civilization

The concept of parallel universes is already astonishing, but here's an even more bizarre idea.

In 2003, philosopher Nick Bostrom, director of the Future of Humanity Institute at the University of Oxford, proposed that our perceived reality—our specific parallel universe—might simply be a digital simulation of another universe. Bostrom estimated that creating a detailed replica of human history would require 10 to the 36th power calculations.

An alien civilization with technology so advanced that it makes us seem primitive could potentially achieve this. Simulating every human who ever lived might not even strain their computational resources, potentially resulting in more simulated beings than real ones [source: Choi and Kestin].

This could imply that we are living in a real-life version of the digital realm depicted in "The Matrix" films.

But there's more. What if the civilization simulating our existence is also a simulation itself?

2: The Concept of Multiverses Has Existed Since Ancient Times

While this isn't definitive proof, it's fascinating to recall the old adage, often credited to Picasso or writer Susan Sontag, that if something can be imagined, it must exist.

There might be truth to this idea. Long before Hugh Everett enjoyed his sherry, many throughout history envisioned various forms of a multiverse.

Ancient Indian scriptures, for instance, are rich with depictions of multiple parallel universes [source: Sanskriti]. In her book "Worlds Without End: The Many Lives of the Universe," Mary-Jane Rubenstein, a religion professor at Wesleyan University, highlights that the ancient Greeks embraced the Atomist philosophy, which proposed an infinite number of worlds dispersed across an equally infinite void.

The concept of multiple universes also found traction in Medieval times. In 1277, the Bishop of Paris contested Aristotle's assertion of a single world, arguing it limited an omnipotent God's ability to create parallel realms. This idea was revived in the 1600s by Gottfried Wilhelm Leibniz, a key figure in the Scientific Revolution, who posited the existence of numerous possible worlds, each governed by distinct physical laws [source: Wilkinson].

1: It Aligns with Our Expanding Understanding of the Universe

As strange as the idea of a multiverse may appear, it aligns with the historical progression of how humans in modern times have come to understand themselves and the cosmos.

As physicists Alexander Vilenkin and Max Tegmark pointed out in a 2011 Scientific American article, western civilization has experienced a series of humbling revelations about reality. Initially, people believed Earth was the center of the universe. Over time, we discovered that even our solar system is just a minor part of the Milky Way.

The multiverse concept takes this pattern to its ultimate conclusion. If multiverses exist, it implies that we are not unique, as there are infinite versions of each of us.

Some believe we are only at the start of an intellectual revolution. Stanford University theoretical physicist Leonard Susskind suggests that future generations may view our era as a golden age, when the limited 20th-century understanding of the universe expanded into a vast, awe-inspiring multiverse [source: Vilenkin and Tegmark].